<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>typeo</title>
</head>
<body>

</body>
<script>
    /*typeo用于判断变量的数据类型*/
        let a = 1;
        let b = "22";
        let c = null;
        let d = 2.111;
        let e = true;
        let f ;
        let g = 100n;
    document.write(typeof (a)+"<br>");
    document.write(typeof (b)+"<br>");
    document.write(typeof (c)+"<br>");
    document.write(typeof (d)+"<br>");
    document.write(typeof (e)+"<br>");
    document.write(typeof (f)+"<br>");
    document.write(typeof (g)+"<br>");

</script>
</html>